I think its probably called the litmus test, it allows to accept or reject certain facets of Sikhism based on the fact that it is fundamentally in opposition to the teachings of the Gurus. Your argument does lack a certain maturity, for instance, can you prove that I am not the author Clive Cussler, and that I wrote all the books by Clive Cussler, no, of course you cannot, so how can we prove beyond all doubt the works and alleged works of the tenth Master? We could be here some time, let us save some time and go with what Sikh Philosophy states, this begs a question, and then we can move forward
do you believe that Guru Gobind Singhji wrote DG in its entirety?
You mean certain facets ATTRIBUTED to Sikhism, because if they don't pass the litmus test, that being in consonance with Gurmat Principles as laid out in Sri Guru Granth Sahib Ji, our ONLY Guru, then those facets can't conceivably be from one of our Gurus. For example, seeing women as 'deceitful' and telling men to distrust women goes against this litmus test because SGGSJ says as Gurmukh to see ALL with a single eye of equality - now the "saying single eye of equality" refers to justice. When applying justice to anyone you have to be fair and equal to everyone, so for a Guru to then lay blame for deceit and immorality on one gender (even if it was just for allegorical purposes) goes against Gurmat. Women are no more prone to deception and immorality than are men. Similarly to say that wives must never do anything without the husband's permission, not even urinate, goes against the Gurmat principle of freedom of every soul - there is no hierarchy of humans . This was a message from Laws of Manu, but not Sikhi - the very message Guru Gobind Singh Ji instilled in initiates when taking amrit is that everyone, regardless of caste, colour, GENDER< rich/poor etc are treated as equals - drinking from the same bata sitting on equal level. There is no longer any hierarchy, and every difference used to delineate and put some above others, were removed. So.... how can that be?? He only meant everyone is equal if they have a p***s?? Doesn't pass the litmus test. Kully suggested earlier that (in his opinion, after having only read a few charitars and that too only for the last 2 months) was that the charitars do not degrade women because Guru Ji only used women as a 'character' to get the deeper message across. However, since Guru Gobind Singh Ji emphasized equality so VERY strongly, it makes no sense that he would then degrade an entire gender just to illustrate a point. In other words, even if you try to say he didn't mean the outward meanings (which are very difficult to ignore), he still would have openly degraded the entire gender just to get his point across. I don't think our Guru was the type to degrade anyone, just to make an unrelated point - nor would he have ever needed to resort to such low behaviour - if he did he certainly did not think much of his Kaurs anyway to throw them under the bus - but I can picture him saying now "oh but I didn't mean it that way"!!! Again, does not pass litmus test.
Also the fact that these supposed deep hidden meanings in Charitropakhyan (and other parts of DG) are the very same messages contained in SGGSJ. So why the need to write the same things again? And that too in a way that creates distrust and contempt towards women in the minds of men... even their own wives? When Guru Ji himself said to see only SGGSJ as our Guru, and ALL the knowledge we would need is contained in SGGSJ? Again, doesn't seem right. All this without even pointing towards sources!